Lost circulation restoring devices



Dec. 24, 1968 H. K. VAN POOLLEN LOST CIRCULATION RESTORING DEVICES 2Sheets-Sheet 1 Filed Dec. 26, 1967 mus/Wok HENDRIK K. VAN POOLLEN 2Sheets-Sheet 2 INVENTOR HENDRIK K. VAN POOLLEN ATTORNEY Dec. 24, 1968 H.K. VAN POOLLEN LOST CIRCULATION RESTORING DEVICES Filed Dec. 26, 1967United States Patent 3,417,824 LOST CIRCULATION RESTORING DEVICESHendrik K. van Poollen, Littleton, Colo., assignor to Marathon OilCompany, Findlay, Ohio, a corporation of Ohio Continuation-impart ofapplication Ser. No. 598,557, Oct. 10, 1966. This application Dec. 26,1967, Ser. No. 693,504

Claims. (Cl. 166-117) ABSTRACT OF THE DISCLOSURE A device for restoringlost circulation in the drilling of a subterranean formation, the devicecomprising a plurality of sealed, flaccid, water-soluble bags containinglost circulation restoring materials, the bags attached in series to awater-insoluble rope strong enough to support the aggregate weight ofsaid bags. The bags can be fitted one inside the other, the inner bagcontaining the lost circulation restoring materials and the compositebeing less water soluble.

CROSS REFERENCES TO RELATED APPLICATIONS This application is acontinuation-in-part of my copending application Ser. No. 598,557, filedOct. 10, 1966, now Patent No. 3,362,476.

BACKGROUND OF THE INVENTION Nature confronts the well driller withdifferent types of lost circulation problems. Sometimes the drillingfluid is lost through minute fissures in rocks. At other times, the bitwill drill into underground rivers. These rivers are swift or slow, andtheir beds fiat or sloping. Subterranean caverns as large as MammothCave may be drilled into, where again, sloping floors may beencountered. Numerous solutions have been proposed to overcome thesedifiiculties. U.S. Patent No. 3,193,373 to Weathersby teaches a processwherein the drilling pipe is placed a short distance above a lostcirculation zone in a well-bore, and rigid four-piece containers castfrom water-soluble materials are injected alternately therein with mudand Water. Weathersby attempts to prevent the rigid containers frombecoming lodged and prematurely blocking the well-bore by using thedrill pipe as an external injector means. However, serious blocking canstill occur in the drill pipe. Injecting such containers Without theprotection of an injector means greatly increases the danger of blockingbecause of numerous rough and uneven spots where the rigid casings cansnag and bridge the well-bore. One of the many advantages of the presentinvention is that such an injection means is not required. Also, thisinvention obviates the costly casting and threading of capsules such asWeathersbys cast containers.

Furthermore, Weathersbys containers are free to move away from theimmediate well-bore vicinity, whereas in my invention, the bagscontaining lost circulation restoring materials are contained withinthat vicinity.

SUMMARY OF THE INVENTION nite, or like materials, and clamped at theother end to effect a sealed bag. Some formation conditions require thatthe bags remain intact for longer periods of time; namely, hotformations which cause the water-soluble material from which they aremade to dissolve at a quicker rate. This problem is overcome byincreasing the thickness of the water-soluble bags, e.g. by usingmultiple bags placed inside one another to effect a predetermined wallthickness. Composite bags can be effected which will dissolve only atthe site of lost circulation.

The water-soluble bags are attached in series to a Water-insoluble ropewhich tends to contain the bags within the immediate vicinity of theWell-bore.

No great inventory of bags is required and a number of bags of one sizecan be fitted, one inside the other, as desired, and tightly clamped toform a protective device of needed water resistance for the particularconditions of a formation. In tubing form, the bags can be flattened andcontained in a small package for shipment or warehousing.

The filled, sealed bags are securely attached to a waterinsoluble ropeby any suitable clamps. A weighted object may be attached to theterminal end of the rope to 'act as an anchor at the bottom of theformation.

DECRIPTION OF THE PREFERRED EMBODIMENTS The water-soluble bags of thisinvention can be made out of many materials. For example, they may becomposed of a polymer film of polyvinyl alcohol, ethylene oxide,polyethylene oxide, dextran, gelatin, methyl cellulose, or the like.

Circulation restoring materials known to the art may be utilized, e.g.dry neat cement, dry bentorn'te, etc. These filler materials may bemodified with quick-setting agents, weight-controlling agents, andreinforcing solids, all of which enhance the utility of the invention.

Any water-insoluble rope which satisfactorily supports the aggregateWeight of all the filled bags aflixed thereon is useful. Such ropesinclude metallic ropes, and nonmetal ropes composed of natural andsynthetic fiber. Example of a metallic rope is a steel wire. A rope madeof hemp typifies the natural fiber rope, whereas a rope composed ofnylon or polyester typifies a synthetic rope.

The attached drawings illustrate my invention. In the attached drawings:

FIGURE 1 is a cross sectional view of a filled bag.

FIGURE 2 depicts a plurality of bags fitted one inside the other, andwherein the innermost bag is filled with circulation restoringmaterials.

FIGURE 3 is a cross sectional view of a Well-bore showing a plurality ofWater-soluble bags attached in series to a Water-insoluble ropedescending into a formation and falling into place around a weightedobject at the terminal end of the rope.

FIGURE 4 shows an integral mass which has set in place at the site oflost circulation within the formation.

FIGURE 5 depicts a drill bit passing through the integral mass; lostcirculation has been restored.

FIGURE 1 shows bag 2 filled with cement 12 and sealed at the top byclamp 8 and at the bottom by clamp 10. The filled bag is attached towater-insoluble rope 14 by clamps 8 (at and 10 (at 10a).

FIGURE 2 shows a plurality of bags fitted one inside the other. Bag 2 isfitted inside bag 4 and bags 2 and 4 fitted inside outer bag 6. Bag 2,the innermost bag, is filled with dry cement 12. All the bags are sealedat the top by clamp 8 and at the bottom by clamp 10. The composite bagis attached to Water-insoluble rope 14 by clamps 8 (at 8a) and 10 (at-10a).

FIGURE 3 shows a plurality of bags of various sizes descending throughborehole 32 into a large, sloping subterraneau formation 16. Larger bags20 form a retaining means for latter, smaller bags 22, 24 and 26, thesebags being of different sizes to fill the interstices between largerbags 20. This particular embodiment, combined with heavy weighted object18 (anchor) attached to the terminal end of water-insoluble rope 14,tend to contain the bags in the area of lost circulation.

In FIGURE 4, the bags have dissolved and water has mixed with cementreleased from the dissolved bags (e.g. cement 12) to form an integralmass 28 within formation 16.

In FIGURE 5, mass 28 has hardened. Drill bit 30 is shown boring its waythrough mass 28; lost circulation within formation 16 has been restored.Well-bore 32 continues through formation 16.

It should be understood that the invention is capable of a variety ofmodifications and variations which will be made apparent to thoseskilled in the art. Such modifications and variations are to be includedwithin the scope of the invention.

What is claimed is:

1. A device for restoring lost circulation in the drilling of asubterranean formation, the device comprising a plurality of scaled,flaccid, water-soluble bags attached in series to a water-insoluble ropestrong enough to support the aggregate weight of said bags when filledwith lost circulation restoring materials.

2. The device of claim 1 wherein a weighted object is attached to theterminal end of the rope.

3. The device of claim 1 wherein a plurality of scaled, flaccid,water-soluble bags are fitted one inside the other to obtain a compositebag having limited water solubility characteristics.

4. The device of claim 3 wherein the composite bag is water soluble atthe site of lost circulation.

5. The device of claim 1 wherein the bags closer to the terminal end ofthe rope are larger than the bags far removed from the terminal end.

6. The device of claim 1 wherein the water-insoluble rope is a metallicrope.

7. The device of claim 1 wherein the water-insoluble rope is anon-metallic rope.

8. The device of claim 1 wherein the water-insoluble rope is a syntheticfiber rope.

9. The device of claim 1 wherein the bags are composed of a polymer filmof polyvinyl alcohol.

10. The device of claim 1 wherein the bags are composed of a polymerfilm of polyethylene oxide.

11. The device of claim 1 wherein the bags are composed of a polymerfilm of cellulosic material.

12. The device of claim 1 wherein the bags are composed of a polymerfilm of dextran.

13. The device of claim 1 wherein the bags are composed of a polymerfilm of gelatin.

14. The device of claim 1 wherein the lost circulation restoringmaterials are comprised of dry bentonite.

15. The device of claim 1 wherein the lost circulation restoringmaterials are comprised of cement.

References Cited UNITED STATES PATENTS 2,504,462 4/1950 Sprague et al166-179 X 2,609,880 9/1952 Dyer 166-21 2,634,098 4/ 1953 Armentrout175-72 2,748,867 6/1956 Lissant 166-42 X 2,768,693 10/1956 Hughes 166-212,824,611 2/1958 Burch 166-57 3,190,373 6/1965 Weathersby 166-117 X3,362,476 1/ 1968 Van Poollen 166-21 STEPHEN I. NOVOSAD, PrimaryExaminer.

US. Cl. X.R.

